Lateral heat spreading for uniform volumetric waste heat production in a single emitter stripe produces a lateral temperature gradient across the emitter. This temperature gradient gives rise to index of refraction changes producing an intra-cavity thermally induced lens that varies with LD power. This, in turn, results in a slow axis divergence that increases significantly with LD power, thereby reducing device brightness significantly with increasing LD power. Slow axis divergence (SAD) measurements show that thermal lensing results in a ˜2× increase in SAD and a corresponding decrease in brightness. Measurements show that SAD increase with LD power is a thermal effect (See FIG. 1).
There is a need for methods for reducing slow axis divergence.